$OpenBSD: patch-tools_gn_args_cc,v 1.5 2017/04/28 14:21:00 robert Exp $
--- tools/gn/args.cc.orig.port	Wed Apr 19 21:06:54 2017
+++ tools/gn/args.cc	Thu Apr 27 19:56:04 2017
@@ -302,6 +302,8 @@ void Args::SetSystemVarsLocked(Scope* dest) const {
   os = "android";
 #elif defined(OS_NETBSD)
   os = "netbsd";
+#elif defined(OS_OPENBSD)
+  os = "openbsd";
 #else
   #error Unknown OS type.
 #endif
